Coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle

ABSTRACT

A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle comprising a stopper head body with a coating thereon so that when the stopper head is in position closing the nozzle and molten metal is introduced into the relatively cold receptacle metal freezes in the bottom of the receptacle and against the coating of the stopper head, the coating being of material which is nonwetting or lubricating with respect to the solidified metal and hence inhibits the adherence of the solidified metal to the stopper head so that when the stopper head is subsequently urged upwardly to permit outflow of molten metal through the nozzle the coating minimizes the adherence of the solidified metal to the stopper head and permits free movement of the stopper head in the bottom of the receptacle. The coating preferably comprises finely divided nonwetting or lubricating refractory material and a binder and is desirably of such consistency that it may be applied by dipping. The coating preferably comprises an unfired nonwetting or lubricating refractory powder. The coating is preferably formed in situ on the stopper head body.

United States Patent [72] Inventor Ronald V. Kilgore Croaopolis. Pa.

Aug. 26, 1968 Jan. 12, 1971 Vesv'ius Crucible Company Swissvale, Pa.

a corporation of Pennsylvania [21 Appl. No. [22] Filed [45] Patented [73] Assignee [54] COATED STOPPER HEAD FOR CONTROLLING OUTFLOW OF MOLTEN METAL THROUGH THE NOZZLE OF A BOTTOM POUR RECEPTACLE 4 Claims, No Drawings [52] US. Cl 251/356 [51] Int. Cl... Fl6k 21/00 [50] Field ot'Search 251/291,

356; l l8/(lnquired); 164/73; 222/544, 559; ll7/5.l(ln part), 5.2(ln part), 5.3(ln part) Primary Examiner-Samuel Scott Attorney-Edward Hoopes, [11

ABSTRACT: A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle comprising a stopper head body with a coating thereon so that when the stopper head is in position closing the nozzle and molten metal is introduced into the relatively cold receptacle metal freezes in the bottom of the receptacle and against the coating of the stopper head, the coating being of material which is nonwetting or lubricating with respect to the solidified metal and hence inhibits the adherence of the solidified metal to the stopper head so that when the stopper head is subsequently urged upwardly to permit outflow of molten metal through the nozzle the coating minimizes the adherence of the solidified metal to the stopper head and permits free movement of the stopper head in the bottom of the receptacle. The coating preferably comprises finely divided nonwetting or lubricating refractory material and a binder and is desirably of such consistency that it may be applied by dipping. The coating preferably comprises an unfired nonwetting or lubricating refractory powder. The coating is preferably formed in situ on the stopper head body.

COATED STOPPER HEAD FOR CONTROLLING OUTFLOW OF MOLTEN METAL THROUGH THE NOZZLE OF ABOTTOM POUR RECEPTACLE This invention relates to a coated stopper head for com trolling outflow of molten metal through the nonle of a bottom pour receptacle. While the invention is of wide application it has especial utility in stopper heads for bottom pour receptacles for pouring or teeming molten metal such as bottom pour ladles and tundishes used for pouring or teeming molten steel either into ingot molds or into continuous casting apparatus. 7

For purposes of explanation and illustration the invention will be described as applied to a stopper head for a bottom pour molten steel ladle or: tundish. When molten steel at a temperature of the order of 2900 F. is introduced into a relatively cold receptacle such as a ladle or tundish having a nozzle in its bottom which is initially closed by a stopper head (see, for example, US. Pat. No. 3,352,534) the great difference in temperature between the incoming molten steel on the one hand and the receptacle, including the nonle and stopper head, on the other hand is so great that some of the molten steel freezes in the bottom of the receptacle. This is a phenomenon well known to those skilled in the art which has existed since the inception of the use of bottom pour receptacles for handling molten steel. The solidified or frozen steel in the bottom of the receptaclefreezes against the stopper head rendering difficult or impossible the raising of the stopper head to permit outflow of molten steel through the nozzle in the bottom of the receptacle. The result is damage to the stopper head in any effort to free it'from the frozen steel which in turn makes imposible optimum control of outflow of steel from the receptacle and in many cases results in inability to shut off the flow at all once the stopper head is unseated.

Various efforts have been made to solve the problem. For example, materials such as sand or lead have been introduced around the stopper head at the upper portion of the nozzle in an attempt to provide a temporary barrier between the stopper head and the initial increment of molten steel entering the receptacle. Such procedures are difficult and cumbersome due to the temperature of .a preheated receptacle which may be of the order of several hundred degrees' Fahrenheit. Moreover they have not satisfactorilyprevented' the molten steel from freezing against the stopper head, and the introduction of such foreign materials is detrimental to the quality of v I have solved the problem by providing a stopper head for controlling outflow of moltenrnetal through the nozzle of a bottom pour receptacle comprising a stopper head body with a coating thereon so that when the stopper head is I in position closing the nozzle and molten metal is introduced into the relatively cold receptacle freezes in the bottom of the receptacle and against the coating of the stopper head, the coating being of material which is nonwetting or lubricat ing with respect to the solidifiedmetal and hence inhibits the adherence of the solidified metal to the stopper head so that when the stopper head is subsequently urged upwardly to permit outflow of molten metal through the nozzle the coating minimizes the adherence of the solidified metal to the stopper head and permits free movement of the stopper head in the bottom of the receptacle. The coating preferably comprises finely divided nonwettingor lubricating refractory material and a binder and is desirably of such consistency that it may be applied by dipping, The coating preferably comprises an unfired nonwetting or lubricating refractory powder. The coating is preferably formed in situ on the stopper head body.

The coating acts with respect to the metal in the nature of to the stopper head.

Nonwettmg or lubricating refractory material may be of various compositions; examples are natural graphite, pyrolytic graphite, amorphous carbon, refractory impregnated paper or any one of the commonly used refractory grains either alone or with one or more of the above mentioned materials. Such material is mixed with a binder to fonn a slurry, mortar, dip coat or wash. The binder may be of various compositions; examples are dextrose, gulac, starch, phosphoric acid or even raw clay. As above stated, the slurry or mixture of finely divided nonwetting or lubricating refractory material and binder is preferably of such consistency that it may be applied by dipping or it may be applied by brushing or spraying. The thickness of the coating may be of the order of one-fourth inch, more or less. p

While I have described certain present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

lclaim: I I

l. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle comprising a stopper head body witha coating thereon so that when the stopper head is in position closing the nozzle and molten metal is introduced into the relatively cold receptacle dipping.

herence of the solidified metal to the stopper head and permits free movement of the stopper head in the bottom of the receptacle.

2, A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle as claimed in claim 1 in which the coating comprises finely divided nonwetting or lubricating refractory material and a binder and is of such consistency that it may be applied by 3. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle as claimed in claim 1 in which the coating comprises an unfired nonwetting or lubricating refractory powder. 

2. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle as claimed in claim 1 in which the coating comprises finely divided nonwetting or lubricating refractory material and a binder and is of such consistency that it may be applied by dipping.
 3. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle as claimed in claim 1 in which the coating comprises an unfired nonwetting or lubricating refractory powder.
 4. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle as claimed in claim 1 in which the coating is formed in situ on the stopper head body. 